This invention relates to fuel flow monitoring apparatus used in conjunction with an electronic fuel-injection control circuit for an internal-combustion engine of the type described in my co-pending U.S. patent application, Ser. No. 120,467 filed Feb. 11, 1980, now U.S. Pat. No. 4,305,451 and my U.S. Pat. No. 4,280,465 issued July 28, 1981. Reference is made to said application and to said United States Patent for greater descriptive detail of a fuel injection engine, to which the present invention is illustratively applicable.
Typically, in fuel-injection control circuits of the character indicated, fuel flow to the engine and total fuel consumption are monitored by a mechanical fuel flow sending unit. Such units, although in wide use, have all of the inherent disadvantages of mechanical systems, are inoperable when the engine is not running and have none of the flexibility and attendent low costs associated with electronic monitoring systems. More particularly, mechanical fuel flow sending units require that a turbine be inserted in the fuel line, risking blockage if the turbine does not operate. The turbine has inherent mechanical inertia which prohibits the instantaneous response characteristic of electronic units. Also, mechanical fuel flow sending units are typically non-linear at low fuel flow rates and must be sized for a particular fuel line.